Polymorphous Luminescent Materials Based on ′T′‐Shaped Molecules Bearing 4,7‐Diphenylbenzothiadiazole Skeletons: Effect of Substituents on the Photophysical Properties

Polymorphism, the intrinsic character of one chemical compound with at least two distinct phase arrangements, plays a very key role in the photophysical properties. In this contribution, four ′T′‐shaped molecules bearing the 2,1,3‐benzothiadiazole (BTD) skeleton, named 5 a–5 d, were prepared and cha...

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Published inChemistry : a European journal Vol. 25; no. 67; pp. 15401 - 15410
Main Authors Qian, Gaowei, Wang, Xiangbing, Wang, Shengyue, Zheng, Yanqiong, Wang, Song, Zhu, Weiguo, Wang, Yafei
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 01.12.2019
Subjects
Calorimetry
Chemical compounds
Chemistry
Differential scanning calorimetry
Diodes
Fluorescence
Light microscopy
Luminescence
Mechanoluminescence
Optical microscopy
Optical properties
Organic chemistry
Organic light emitting diodes
Photoluminescence
Polymorphism
Quantum efficiency
Stability analysis
Thermal stability
Thermogravimetric analysis
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Summary:Polymorphism, the intrinsic character of one chemical compound with at least two distinct phase arrangements, plays a very key role in the photophysical properties. In this contribution, four ′T′‐shaped molecules bearing the 2,1,3‐benzothiadiazole (BTD) skeleton, named 5 a–5 d, were prepared and characterized. All compounds exhibited excellent thermal stability and polymorphism in the solid state, evident from thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy results. Intense emissions with high photoluminescent quantum yields were achieved both in solution (56–97 %) and neat films (33–98 %). All compounds possessed clearly pH‐dependent luminescence properties in solution. Additionally, compound 5 d showed useful mechanochromic luminescence owing to the transformation between the crystal and amorphous state. Employing compounds 5 a–5 d as the dopant, solution‐processable organic light‐emitting diodes (OLEDs) were fabricated and presented a highest external quantum efficiency of 6.15 %, which is higher than the theoretical value of fluorescence‐based OLEDs (∼5 %). This research provided a novel strategy for designing high‐efficiency BTD‐based polymorphic luminescent materials.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201904026